Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The suprachiasmatic nuclei (SCN) contain a circadian system consisting of circadian oscillator (clock) that is normally synchronized by the light/dark cycle (input) and drives circadian rhythms (output) that are intrinsic to the SCN. Gene expression of immediate-early genes, such as c-fos and jun-B, in the ventrolateral SCN is associated with circadian synchronization by light pulses and subjected to circadian control. Vasopressin and somatostatin gene expression shown distinct circadian rhythms intrinsic to the dorsomedial SCN with higher peptide levels occurring during the day. In addition, embryonic SCN grafted into the brain of an SCN-lesioned arrhythmic host define the period of the restored circadian locomotor rhythm. Taken together, these and other findings support the notion that the expression of genes underlying circadian synchronization, oscillation and output takes place within individual SCN neurons. However, no information regarding the nature and number of those neurons as well as the molecular mechanisms of the single cell-circadian oscillator and output is currently available. Therefore, we propose a simple two-neuron model as a framework for critically discussing the molecular genetic strategies to analyze the circadian system in SCN.
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PMID:Gene expression in suprachiasmatic nucleus and circadian rhythms. 798 50

The aim of this study was to evaluate the effects of octreotide, a long-acting somatostatin analogue, on canine gastric mucosal blood flow and hemodynamics. We hypothesized that octreotide might decrease gastric mucosal blood flow without causing adverse hemodynamic effects. Two groups of dogs were anesthetized (six normal dogs and six dogs with prehepatic portal hypertension), and each dog was administered intravenous octreotide, normal saline solution, and vasopressin for 30 minutes on separate days in a blinded, randomized fashion. Vasopressin was included as treatment for a positive control. Gastric mucosal blood flow was assessed at the fundus, corpus, and antrum by endoscopic reflectance spectrophotometry. A femoral arterial catheter monitored systemic blood pressure and heart rate. Treatment responses for all observations were calculated for each dog as a percentage of baseline values. For mucosal blood flow, treatment responses did not differ significantly over time or between animal group or gastric location. Octreotide significantly decreased indices of hemoglobin concentration (-19%, p = 0.01) and oxygen saturation (-17%, p = 0.0002) compared to saline (-9% and -7%, respectively). The mean arterial pressure was increased after octreotide compared to saline (+23% versus +7%, p = 0.01), but octrotide had no effect on heart rate (+2% versus +1%). Vasopressin also decreased the indices of hemoglobin concentration (-34%) and oxygen saturation (-82%) significantly more than saline (p = 0.001). Vasopressin increased mean arterial pressure (+55%), but also caused reflex bradycardia (-22%) significantly more than saline (p = 0.001). We conclude that octreotide decreases canine gastric mucosal blood flow and appears to cause minimal hemodynamic changes.
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PMID:Octreotide decreases canine gastric mucosal blood flow: a controlled assessment by endoscopic reflectance spectrophotometry. 816 36

A systematic review of available treatments for controlling active variceal bleeding provides important guidelines for choosing an overall strategy. The initial prerequisite of a diagnostic endoscopy provides the opportunity for early intervention with local endoscopic techniques, such as injection sclerotherapy, direct intravariceal injection of tissue adhesives and banding ligation of varices. This approach currently represents the optimal strategy. If the endoscopic expertise is not available, the use of vasoactive drugs may provide temporary control of bleeding while allowing time for more definitive treatment. Vasopressin and its analogues are the most widely used vasoactive drugs, but somatostatin holds promise. In view of the systemic haemodynamic complications associated with vasopressin (and probably glypressin), these drugs should be given in combination with nitrates. Balloon tamponade remains an important alternative for patients in whom massive, life-threatening haemorrhage has occurred. Surgical techniques, such as shunting and devascularisation, are increasingly reserved for the management of variceal bleeding that endoscopic therapy has failed to control.
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PMID:The management of active variceal bleeding. 849 68

Many peptides have been shown to modulate nutrient intake. In most cases, these peptides decrease food intake, but in a few cases they have been demonstrated to stimulate feeding. Infusion of insulin peripherally will decrease food intake unless hypoglycemia occurs where the reduced glucose is a stimulus to feeding. Other pancreatic hormones including glucagon, amylin, pancreatic polypeptide, and enterostatin reduce food intake. Of the gastrointestinal hormones, cholecystokinin has been the most widely studied and reduces food intake in a number of species, including human beings. Gastrin-releasing peptide and its relative bombesin have been shown to decrease food intake in experimental animals and man. Somatostatin reduces food intake in experimental animals, but no clinical studies are available. Four pituitary peptides also modify food intake. Vasopressin decreases feeding. In contrast, injections of desacetyl melanocyte stimulating hormone (dMSH), growth hormone, and prolactin are associated with increased food intake. Finally, there are a group of miscellaneous peptides which modulate feeding. beta-casomorphin, a hepta peptide produced during the hydrolysis of casein, stimulates food intake in experimental animals. In contrast, the other peptides in this group including calcitonin, apolipoprotein A-IV, the cyclized form of histidyl-proline, several cytokines, and thyrotropin-releasing hormone decrease food intake. Many of these peptides act on gastrointestinal or hepatic receptors which relay messages to the brain via the afferent vagus nerve. As a group they provide a number of leads for potential drug development.
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PMID:Nutrient intake is modulated by peripheral peptide administration. 869 60

We investigated the characteristics of GABAergic neurons in the rat suprachiasmatic nucleus (SCN) in normal untreated rats by examination of co-expressed peptides. We adopted double labeling in situ hybridization using a digoxigenin-labeled glutamic acid decarboxylase (GAD) riboprobe and 35S-labeled peptide riboprobes. GAD mRNA-positive neurons were distributed throughout the SCN from the rostal to the caudal pole. In the dorsomedial part of the SCN, most GAD mRNA-positive neurons co-expressed arginine vasopressin mRNA. In the ventrolateral part of the SCN, about two thirds of GAD mRNA-positive neurons co-expressed vasoactive intestinal peptide (VIP) mRNA. Co-expression of GAD and somatostatin mRNA was observed in virtually all neurons of the intermediate part of the SCN. In contrast, these peptidergic traits were poorly expressed in hypothalamic GABAergic neurons outside the SCN. Vasopressin mRNA-positive cells in the supraoptic nucleus did not express GAD mRNA, and co-expression of somatostatin mRNA and GAD mRNA was rare in the periventricular hypothalamic nucleus. Similarly, the VIP mRNA co-expression ratio of GABAergic neurons in the cerebral cortex was far lower than that in the SCN.
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PMID:Peptide expression in GABAergic neurons in rat suprachiasmatic nucleus in comparison with other forebrain structures: a double labeling in situ hybridization study. 928 10

The search for new pharmaceutical treatments has led to the isolation of products from a range of natural sources. Analogues synthesized from these products may possess an improved therapeutic effect over their natural counterparts. Two natural peptides, vasopressin and somatostatin, possess pronounced in vivo effects, so do their analogues terlipressin and octreotide. Vasopressin is a powerful vasopressor, reducing portal pressure, and has been used to treat gastrointestinal haemorrhages. However, a number of adverse cardiovascular effects resulting from an increase in peripheral vascular resistance have been associated with this drug. Terlipressin, however, is more effective, has an improved safety profile and is associated with fewer side effects than vasopressin. Somatostatin, a growth regulatory hormone, achieves haemostasis by decreasing splanchnic blood flow, and is effective in preventing early rebleeding. Somatostatin is effective in treating bleeding oesophageal varices (BOV) and is associated with fewer and more transient side effects than terlipressin. Octreotide, however, has greater stability and a longer half-life than somatostatin, but has a less favourable safety profile. Octreotide displays a number of therapeutic advantages over somatostatin, but not in the treatment of gastrointestinal indications. The development of terlipressin from vasopressin has demonstrated a number of clinical advantages, while the development of octreotide from somatostatin has not shown any significant advantage in the treatment of BOV.
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PMID:Development of analogues: successes and failures. 959 98

Vasopressin (VP) is one of the principal transmitters in the suprachiasmatic nucleus (SCN). Approximately 20% of neurones in the dorsomedial division of the SCN synthesize the peptide and a high proportion of SCN neurones (> 40%) are excited by VP acting through the V1 receptor. This suggests that VP may act as a feedback regulator of electrical activity within the nucleus. Such an intrinsic excitatory signal can be demonstrated by perifusion with a V1 antagonist which reduces spontaneous neural activity. As the synthesis and release of VP occurs in a circadian manner, this leads to a variable feedback excitation which may contribute to the circadian pattern of activity of the neural clock. This role in amplifying rhythmicity is supported by observations that animals deficient in VP show a reduced circadian amplitude of behavioural rhythms (e.g. locomotor and cortical electroencephalographic rhythms). VP expression declines during ageing and although aged animals show no change in the proportion of SCN neurones excited by VP, the rhythm of spontaneous electrical activity shows a progressive decline, consistent with the reduced endogenous excitatory feedback. However, the homozygous Brattleboro rat which lacks any VP expression still maintains rhythms of electrical activity, indicating that VP is not the sole factor generating circadian activity. The generation of this rhythmicity may depend upon the interaction of VP with other transmitter systems, such as the inhibitory transmitters somatostatin and GABA which show a circadian variation in efficacy. In addition to its role in feedback amplification of the endogenous rhythm of electrical activity, VP also functions as part of the efferent signal to the rest of the CNS where it potentially regulates a number of behavioural and physiological rhythms, including the circadian activity of the hypothalamo-pituitary-adrenal axis. Thus, the combined amplification and signalling functions makes VP an important component of the neuronal clock function in mammals.
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PMID:Vasopressin neurotransmission and the control of circadian rhythms in the suprachiasmatic nucleus. 1007 99

It was investigated whether grafts of the suprachiasmatic nucleus could re-instate circadian rhythmicity in the absence of its endogenous vasopressin production and whether the restored rhythm would have the long period length of the donor. Grafts of 17-days-old vasopressin-deficient homozygous Brattleboro rat fetuses, homotopically placed in arrhythmic suprachiasmatic nucleus-lesioned Wistar rats, re-instated circadian drinking rhythm within 20-50 days similar as seen for grafts of heterozygous control fetuses. Period length of the recovered rhythm revealed a similar difference (average 24.3 vs. 23.8 h) as reported for the rhythm between the adult Brattleboro genotypes. In all transplants, also those of the two-third non-recovery rats, a surviving suprachiasmatic nucleus was visible as a vasoactive intestinal polypeptide-positive neuronal cell cluster, whereas heterozygous transplants also revealed the complementary vasopressinergic cell part. Explanation of the absence of recovery failed since no undisputable correlation emerged between recovery of rhythm and vasoactive intestinal polypeptide, vasopressin and/or somatostatin immunocytochemical characteristics of the suprachiasmatic nucleus of the transplant. Special focus on the somatostatinergic neurons revealed their presence only occasionally near or in between the vasoactive intestinal polypeptidergic and (in the case of heterozygous grafts) vasopressinergic cell cluster. However their aberrant cytoarchitectural position appeared not to have affected the possibility to restore drinking rhythm of the suprachiasmatic nucleus-lesioned arrhythmic rat. It was concluded that grafted Brattleboro fetal suprachiasmatic nucleus develop their intrinsic rhythm conform their genotype and that vasopressin is not a crucial component in the maintenance nor in the transfer of circadian activity of the biological clock for drinking activity. Vasopressin of the suprachiasmatic nucleus may instead serve modulation within the circadian system.
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PMID:Vasopressin-deficient suprachiasmatic nucleus grafts re-instate circadian rhythmicity in suprachiasmatic nucleus-lesioned arrhythmic rats. 1007 20

The medical treatment of portal hypertension has experienced a marked progress in the past decade due to the introduction of effective portal hypotensive therapy. This has been possible because of the better understanding of the pathophysiological mechanisms leading to portal hypertension. A major step forward was the introduction of beta-blockers for the prevention of bleeding and rebleeding from gastroesophageal varices. Effective therapy requires the reduction of the hepatic venous pressure gradient (HVPG) to 12 mmHg or below, or at least by 20% of baseline values. Unfortunately, this is only achieved in 1/3 to 1/2 of patients. Combination therapy, associating isosorbide-5-mononitrate and propranolol or nadolol administration enhances the reduction in portal pressure and increases the number of patients in whom HVPG decreases by more than 20% of baseline values and below 12 mmHg. Randomized clinical trials (RCT's) do support the concept that combination therapy is more effective than propranolol or nadolol alone, significantly better than sclerotherapy, and probably than endoscopic banding ligation. Therapy may be complemented by the association of spironolactone. The main inconvenience of pharmacological therapy is that there is no non-invasive method available to detect non-responders to treatment. Failures of drug therapy should be managed endoscopically. Failures of endoscopic treatment require 'rescue' by means of TIPS or shunt surgery. Patients with advanced liver failure should be considered for orthotopic liver transplantation, and put into a waiting list if eligible. In the treatment of acute variceal bleeding pharmacological therapy offer the unique advantage of allowing to provide specific therapy immediately after arrival to hospital, or even during transferral to hospital by ambulance, since it does not require sophisticated equipment and highly qualified medical staff. Vasopressin has been abandoned because of its toxicity, although this can be reduced by the combined administration of transdermal nitroglycerin. Terlipressin has longer effects and is more effective and safer than vasopressin alone or in combination with nitroglycerin. It has proved to be effective and to decrease mortality from bleeding in double-blind studies. RCT's have shown that this drug is as effective and safer than emergency sclerotherapy. Therapy should be maintained for five days to prevent early rebleeding. Somatostatin is probably as effective as terlipressin. Octreotide is probably useful after endoscopic therapy but can not be recommended as first line treatment. Endoscopic injection sclerotherapy and endoscopic banding ligation are very effective, but require well trained medical staff. There is an increasing trend for initiating therapy with a pharmacological agent, followed by semi-emergency endoscopic therapy as soon as a well trained endoscopist is available (within 12-24 hours), while maintaining drug therapy for 5 days. Failures of medical therapy may be treated by a second session of endoscopic treatment, but if this fails TIPS of emergency surgery should be done. In high-risk situations, such as bleeding from gastric varices or in patients with advanced liver failure, the decision for TIPS or surgery should be done earlier, after failure of the initial treatment.
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PMID:The sixth Carlos E. Rubio Memorial Lecture. Prevention and treatment of variceal hemorrhage. 1076 Dec 6

Vasopressin (AVP) receptors present in In-R1-G9 cells, a hamster glucagon-secreting alpha-pancreatic cell line, were characterized using SSR-149415, a selective nonpeptide V1b receptor antagonist, and reference AVP compounds. Binding experiments, using [3H]AVP as a ligand, identified a single population of high-affinity binding sites. SSR-149415 competitively inhibited this binding and exhibited nanomolar and stereospecific affinity for these sites. The affinity of various AVP/oxytocin ligands confirmed a V1b binding profile. In functional studies, AVP was a potent stimulant in inducing intracellular Ca2+ increase, glucagon secretion, and cell proliferation. These effects were fully antagonized by SSR-149415 with a nanomolar potency, whereas its diasteroisomer as well as two selective V1a and V2 receptor antagonists were much less potent. Additionally, the order of potency of AVP agonists and antagonists was in agreement with V1b-mediated effects. By RT-PCR, we confirmed the presence of V1b receptor mRNA in both In-R1-G9 cells and in human pancreas. The distribution pattern of V1b receptors investigated in human pancreas by immunohistochemistry showed strong labeling in islets of Langerhans, and colocalization studies indicated that this receptor was expressed in alpha-glucagon, beta-insulin, and somatostatin pancreatic cells. Thus, in In-R1-G9 cells, AVP mediates intracellular Ca2+ increase, glucagon secretion, and cell proliferation by activating V1b receptors, and these effects are potently antagonized by SSR-149415. Moreover, the presence of V1b receptors also found in human Langerhans islets could suggest hormonal control of AVP in human pancreas.
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PMID:Pancreatic vasopressin V1b receptors: characterization in In-R1-G9 cells and localization in human pancreas. 1273 62


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